Electronic systems commonly include many different electronic circuits which must communicate data with each other through suitable data transmission lines or networks. A simple data communication arrangement includes a separate transmission line for each individual signal which must be communicated from one circuit to another. However, as integrated circuit technology has advanced, far more circuitry can be placed on an integrated circuit chip than can be accessed externally through separate signal transmission lines. An integrated circuit package will inevitably have room for fewer input/output pins than the number of signals which must be communicated to a separate integrated circuit or received from a separate integrated circuit.
Time division multiplexing may be used to allow different signals to effectively share a common transmission line. In time division multiplexing, a single transmission line carries one signal at one time and another signal at another time. However, time division multiplexing adds complexity to the circuit. Furthermore, since signals are not communicated simultaneously, time division multiplexing reduces the overall speed of data communications.
U.S. Pat. No. 5,761,246 discloses a circuit and signal transmission method in which a number of different signals may be communicated from one circuit to another simultaneously over a single signal transmission line. However, the arrangement shown in the U.S. Pat. No. 5,761,246 facilitates only unidirectional signal transmission. That is, although multiple signals from one circuit are communicated simultaneously to a second circuit over a single transmission line, a separate transmission line was required for transmitting signals from the second circuit back to the first circuit.
U.S. Pat. No. 4,604,740 discloses a digital transceiver allowing full duplex or bi-directional transmission of digital signals over a common transmission line. This transceiver is limited to only bi-directional transmission between two circuits, and does not facilitate multi-directional communications between three or more circuits.